Lyudmila Todorova

Using Phi Coefficient to Interpret Results Obtained by InterCriteria Analysis

The authors propose an algorithm for assessment of the estimates of “correspondence” and “opposition” obtained by InterCriteria Analysis (ICA) in the form of intuitionistic fuzzy vector pairs. For this aim the modified Pearson coefficient of Karl Pearson, called \(\varphi \) coefficient (“mean square contingency coefficient”). The algorithm is applied on real data from neurosurgery. The statistical significance of the relations between the considered criteria is verified by data found in literature. The authors believe this approach for data exploration may prove useful in many areas.

Thin films from hydrophilic poly(N,N-dimethyl acrylamide) copolymers as optical indicators for humidity

In the present paper we study thin films from poly(N,N-dimethyl acrylamide)-poly(ethylene oxide) (PDMAA/PEO) copolymers of different composition and structure in order to implement them as sensitive media for optical indicators for humidity. PDMAA/PEO di- and triblock copolymers were synthesized via redox polymerization in aqueous media. Thin films were deposited on silicon substrates by spin coating method using polymers solutions with appropriate concentrations. Refractive index, extinction coefficient and thickness of the films are calculated from reflectance spectra of the films deposited on silicon substrates using non-linear curve fitting method. Sensing properties of the films were tested by films exposure to different humidity levels followed by in-situ monitoring of the changes in the optical properties. The influence of the polymer structure and postdeposition annealing on the optical and sensing properties of the films was investigated. The potential application of selected polymers for optical sensing of humidity were demonstrated and discussed.

Color sensing of humidity using thin films of hydrophilic cationic opolymers

The possibility for color sensing of humidity at room temperature using thin films from hydrophilic cationic block copolymers of different compositions and thickness is demonstrated. Diblock copolymers of composition poly [(ethylene oxide)-b-(N, N-dimethyl acrylamide)] (PEO-b-PDMAA), the PDMAA block being modified with different amounts of quaternary ammonium groups, are synthesized via redox copolymerization in aqueous media. Silicon wafers and Bragg stacks are used as substrates for spin-coating of thin polymers films with thickness in the range 50–200 nm. The color change is quantified through calculation of CIE tristimulus color coordinates using reflectance spectra of the films measured at relative humidity (RH) of 5% and 97%. The influence offilm thickness, substrate type and chemical modification on the humidity sensitivity and color change of the films is demonstrated and discussed.

Optic Nerve Glioma in Two Sisters with Family History of Neurofibromatosis Type 1

&NA; Optic nerve glioma (ONG) is associated in 10% of patients with neurofibromatosis (NF) type 1. To date no consensus has been reached regarding the therapeutic approach and prevention of visual impairment in these patients. Reports in the literature vary from a conservative approach (observation) to the use of single treatment modalities or multimodality protocols of surgical removal, radiotherapy, and/or chemotherapy. We present our experience with two siblings with ONG whose mother carries cutaneous stigmata of NF type 1. The younger sister was diagnosed 3 years after the treatment of the older sibling following recommended imaging for screening. Postoperative follow‐up for 11 and 15 years, respectively, demonstrated lack of tumor regrowth and preserved vision in the contralateral eye. We discuss the treatment strategy in pediatric patients with orbital ONG associated with NF type 1.

Generalized Net Model for Monitoring the Degree of Disability in Patients With Multiple Sclerosis Based on Neurophysiologic Criteria

Multiple sclerosis (MS) is a chronic disease of the central nervous system, which affects most often the young age. The disease has a social importance, as it leads to disability in active age. The course of the disease is individual and requires an adequate approach in selecting the appropriate treatment strategy. This requires periodic monitoring of the patients for early registration of the disease progression. Most commonly used tests are clinical investigation, brain MRI and other paraclinical methods, including neurophysiological assessment (usually evoked potentials). Evoked potential (EP) is a reliable method for quantifying the severity of damage to the white matter in patients with MS. The aim of this study is to develop a model for Generalized NET (GN)-registration of the direction of the course of disease based on neurophysiological evaluation of multimodal evoked potentials. Also, to make a comparison of the results obtained by the EP with the degree of disability as measured by the scale of Kurtzke (Expanded disability Status Scale-EDSS). We have followed up 48 patients with clinically definite MS over a period of 1 year. The patients were tested both clinically and neurophysiologically at Clinic of Neurology in MHAT- NHH, Sofia. The three main modalities evoked potentials were applied: visual evoked potentials with reversive pattern (VEPRP); Brainstem auditory evoked potentials (BAEP); Somatosensory evoked potentials (SSEP), taken during stimulation of median nerve. As a result it is established that the abnormalities of EP correlate significantly with the clinical findings. Based on the obtained results is developed a GN-model generating candidate predictive rules for the progression of the illness. In the end it has been found that abnormalities of EP significantly correlated with clinical findings. Based on the obtained results a GN model was developed. The model has a high sensitivity (SEN), specificity (SPE), PPV (Positive predictive value) and NPV (Negative predictive value) for the disease progression.

DYNAMIC CHANGES OF VISUAL EVOKED POTENTIALS AND BRAINSTEM AUDITORY EVOKED POTENTIALS IN PATIENTS WITH MULTIPLE SCLEROSIS

Evoked potentials are widely used in diagnosis of multiple sclerosis (MS), but not sufficient data are available for their prospective role in the course of disease. The presentation is a longitudinal study in the Clinic of Neurology at MHAT – NHH – Sofia from Aug 2009 to Mar 2012. It includes 52 patients with clinically definite multiple sclerosis according to revised MacDonald criteria (2005/2010). Paternal visual evoked potentials (PVEP) and brainstem auditory evoked potentials (BAEP) were examined consecutively during the study and these results were compared with the grade of disability according to Expanded Disability Statement Scale (EDSS). The follow-up was done at registered relapses and also at patients without new complaints – one or two years since the initial examination. For quantitative assessment of pathological EP changes, a total evoked potential (EP) score was formulated. This score is a sum of the individual PVEP and BAEP scores. The time interval to the first change of total EP score and the time interval to the first change in EDSS were assessed. The results were compared to Kaplan–Meier survival curves. We found more prominent sensitivity of the total EP score compared to EDSS in the course of disease. Our study concludes that the neurophysiologic method is more sensitive test than EDSS for earlier detection of deterioration and disease progression.